<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    h1{
        /* 用于学习测试 */
        /* color: red;
         */
         /* color:rgb(0,255,0); */

        background-color: aqua;
         /* 半透明形式 */
         /* color:rgba(0,0,0,0.3); */

         /* color:rgba(0,0,0,0.8); */

         color: #00ff00;


    }
</style>
<body>
    <h1>h1 标签</h1>
</body>
</html>